#include <iostream>
#include <string>
#include <jsoncpp/json/json.h>

using namespace std;

int main()
{
    int x = 10;
    int y = 20;
    char z = '+';

    Json::Value root;
    root["x"] = x;
    root["y"] = y;
    root["op"] = z;

    // Json::StyledWriter writer;
    Json::FastWriter writer;
    string s = writer.write(root);
    cout << s << endl;

    return 0;
}